US6054224AExpiredUtility

Polyester film for electrical insulation

81
Assignee: TORAY INDUSTRIESPriority: Aug 25, 1997Filed: Aug 25, 1997Granted: Apr 25, 2000
Est. expiryAug 25, 2017(expired)· nominal 20-yr term from priority
Inventors:Itsuo NagaiSeizo AokiYukichi Deguchi
H01B 3/422H01B 3/441H01B 3/42Y10S181/403Y10T428/31721Y10T428/31681Y10T428/31786Y10T428/12569C08J 5/18
81
PatentIndex Score
47
Cited by
27
References
32
Claims

Abstract

An electrical insulating polyester film has an apparent density of 1.37 to 0.85 g/cm 3 and a tensile modulus of 2.0 to 4.5 GPa. A film having low oligomer content, low cost, high heat resistance, high impact resistance, superior machinability and processability, assembling stability, and superior visibility is obtained. Furthermore, leakage of current is reduced when it is used for motor insulation.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. An electrical insulating polyester film having an apparent density of 1.37 to 0.85 g/cm 3  and a tensile modulus of 2.0 to 4.5 GPa. 
     
     
       2. An electrical insulating polyester film according to claim 1, wherein a polyester resin constituting the polyester film has an intrinsic viscosity of 0.6 to 1.5 dl/g. 
     
     
       3. An electrical insulating polyester film according to claim 1, wherein the ratio Y/D of the tensile modulus Y (GPa) to the apparent density D (g/cm 3 ) of the film satisfies the relationship 2.5<Y/D<4. 
     
     
       4. An electrical insulating polyester film according to claim 1, wherein the polyester film has a multilayered configuration comprising a base layer and a surface layer provided on at least one surface thereof. 
     
     
       5. An electrical insulating polyester film according to claim 4, wherein the intrinsic viscosity of a polyester resin constituting the polyester film is 0.6 to 1.5 dl/g. 
     
     
       6. An electrical insulating polyester film according to claim 4, wherein the Y/D ratio of the tensile modulus Y (GPa) to the apparent density D (g/cm 3 ) of the film satisfies the relationship 2.5<Y/D<4. 
     
     
       7. An electrical insulating polyester film according to claim 4, wherein the apparent density of the surface layer is greater than the apparent density of the base layer. 
     
     
       8. An electrical insulating polyester film according to claim 4, wherein the thickness of the surface layer occupies 5 to 50% of the total thickness of the film. 
     
     
       9. An electrical insulating polyester film according to claim 4, wherein the film is produced by melting polyester resins constituting a base layer and a surface layer, conjugating these layers, extruding them through a die, cooling them, and stretching the film in biaxial directions. 
     
     
       10. An electrical insulating polyester film according to claim 4, wherein polyester resins for forming the base layer and the surface layer comprise polyethylene terephthalate. 
     
     
       11. An electrical insulating polyester film according to claim 4, wherein polyester resins for forming the base layer and the surface layer comprise polyethylene 2,6-naphthalate. 
     
     
       12. An electrical insulating polyester film according to claim 4, wherein a polyester resin for forming the base layer contains a polymer or fine particle incompatible with the polyester resin. 
     
     
       13. An electrical insulating polyester film according to claim 12, wherein the incompatible polymer is polyolefin. 
     
     
       14. An electrical insulating polyester film according to claim 13, wherein the polyolefin is polypropylene or polymethylpentene. 
     
     
       15. An electrical insulating polyester film according to claim 1, wherein the film has a dielectric constant of 2.2 to 3.0. 
     
     
       16. An electrical insulating composite film comprising a heat-resistant film laminated on at least one face of a polyester film according to claim 1, the heat-resistant film having heat resistance higher than that of the polyester film. 
     
     
       17. An electrical insulating composite film according to claim 16, wherein the heat-resistant film having heat resistance higher than that of the polyester film is laminated on the two faces of the polyester film. 
     
     
       18. An electrical insulating composite film according to claim 16, wherein the polyester film comprises polyethylene terephthalate, and the heat-resistant film comprises polyphenylene sulfide or polyethylene naphthalate. 
     
     
       19. An electrical insulating composite film according to claim 17, wherein the polyester film comprises polyethylene terephthalate, and the heat-resistant film comprises polyphenylene sulfide or aromatic polyimide. 
     
     
       20. An electrical insulating composite film according to claim 16, wherein the composite film has an apparent density of 1.37 to 0.85 g/cm 3  and a tensile modulus of 2.5 to 5.0 GPa. 
     
     
       21. An electrical insulating composite film according to claim 17, wherein the composite film has an apparent density of 1.37 to 0.85 g/cm 3  and a tensile modulus of 2.5 to 5.0 GPa. 
     
     
       22. An electrical insulating composite film according to claim 16, wherein a polyester resin constituting the polyester film has an intrinsic viscosity of 0.6 to 1.5 dl/g. 
     
     
       23. An electrical insulating composite film according to claim 16, wherein the Y/D ratio of the tensile modulus Y (GPa) to the apparent density D (g/cm ) of the composite film satisfies the relationship 3.0<Y/D<4.5. 
     
     
       24. An electrical insulating composite film according to claim 16, wherein the dielectric constant is 2.4 to 3.0. 
     
     
       25. An insulating system in which an electrical insulating polyester film according to claims 1 is used for electrical insulation in an environment comprising a refrigerating medium of partially-hydrogenated halogenated carbon as a primary component and a polar oil. 
     
     
       26. An insulating system in which an electrical insulating polyester film according to claim 15 is used for electrical insulation in an environment comprising a refrigerating medium of partially-hydrogenated halogenated carbon as a primary component and a polar oil. 
     
     
       27. An insulating system in which an electrical insulating polyester film according to claim 16 is used for electrical insulation in an environment comprising a refrigerating medium of partially-hydrogenated halogenated carbon as a primary component and a polar oil. 
     
     
       28. An insulating system in which an electrical insulating polyester film according to any one of claims 17 to 24 is used for electrical insulation in an environment comprising a refrigerating medium of partially-hydrogenated halogenated carbon as a primary component and a polar oil. 
     
     
       29. An hermetic-type compressor comprising a motor in which an insulating system according to claim 25 is used for insulating an exciting coil. 
     
     
       30. An hermetic-type compressor comprising a motor in which an insulating system according to claim 26 is used for insulating an exciting coil. 
     
     
       31. An hermetic-type compressor comprising a motor in which an insulating system according to claim 27 is used for insulating an exciting coil. 
     
     
       32. An hermetic-type compressor comprising a motor in which an insulating system according to claim 28 is used for insulating an exciting coil.

Cited by (0)

No later patents cite this yet.

References (0)

No backward citations on record.